Somatostatin, or somatotropin-release inhibition factor, is a neuropeptide inhibiting the release of the growth hormone (somatotropin).
A number of somatostatin synthetic analogues are known, which are used in human and animal therapies.
In particular, octreotide has been known for some time, which is a somatostatin synthetic analogue used in therapy for the treatment of syndromes due to gastroenteral-pancreatic endocrine tumours, acromegaly as well as in the post-surgery treatment after pancreas surgery. Octreotide is also indicated as an agent inhibiting gastric secretion. This compound is described in U.S. Pat. No. 4,395,403 (Sandoz) and has the formula: ##STR2##
The octapeptide described above lies within a general formula of monocyclic polypeptides, comprising an hexapeptide residue containing a phenylalanine residue, optionally substituted at the 1-position of the aromatic ring, a cysteine residue at the 2-position, a D-trypthophan residue optionally substituted at the 4-position of the indole ring, a lysine residue at the 5-position, optionally N-alkylated at the position .epsilon., an amino acid residue at the 6-position and a cysteine residue at the 7-position, the two sulfur atoms of the 2 and 7 cysteine residues are linked together and an amino acid residue at the 8-position.
Another somatostatin synthetic analogue, known under the name of Lanreotide, has been recently used in therapy. This compound has formula: ##STR3##